1. Field of the Invention
The present invention relates to a sheet feeding device configured to feed sheets and an image forming apparatus equipped with the same.
2. Description of the Related Art
Generally speaking, an image forming apparatus such as a copying machine, a printer, or a facsimile apparatus has, in the image forming unit thereof, a sheet feeding device configured to feed sheets. The sheet feeding device is equipped with a sheet storage unit storing sheets to be fed, and the sheet storage unit can be drawn out of the apparatus main body so that the user can replenish the sheet storage unit with sheets.
Japanese Patent Application Laid-Open No. 2010-241527 discusses a sheet feeding device having a stacking unit which can be drawn out of the feeding device and on which sheets are stacked, a cassette detection unit configured to detect whether the sheet stacking unit is attached to the feeding device, a drive unit configured to raise the stacking unit, and a sheet presence detection unit configured to detect whether sheets are stacked on the stacking unit.
In the sheet feeding device discussed in Japanese Patent Application Laid-Open No. 2010-241527, in the case where the sheet presence detection unit detects the presence of sheets when it is detected by the cassette detection unit that the stacking unit has been attached to the feeding device, it is determined that the stacking unit is overloaded with sheets.
In the sheet feeding device discussed in Japanese Patent Application Laid-Open No. 2010-241527, when it is determined that there is overloading, the feeding operation is inhibited, whereby it is possible to prevent defective sheet feeding in the case of overloading.
However, in the sheet feeding device discussed in Japanese Patent Application Laid-Open No. 2010-241527, there is the possibility of erroneous detection of overloading in a case as follows.
That is, in a case where the user draws the stacking unit out of the feeding device only by a small amount, and attaches it to the feeding device again, the stacking unit remains raised by a drive unit, and the sheet presence detection unit detects the presence of a sheet. That is, in the sheet feeding device discussed in Japanese Patent Application Laid-Open No. 2010-241527, it may be erroneously determined that there is overloading although, in fact, there is no overloading.